Excessive Fuel Consumption

[Louis069]

Hi guys, I have just purchased a 2008 Ec250 with a fmf gnarly pipe it's a great bike a lot better than my old Yamaha ttr250.

Anyway I cleaned the carb when I brought it and it's running good apart from the fact it uses almost the whole 9.5 litre tank in about 40km or 3 hours of about half fire roads and half woods. Bearing in mind I'm not flogging it the whole way.
I only found this strange as my brothers kdx 200 only uses about 4.5 litres on the same ride.

The main jet is 175 and a 35 pilot not sure about the needle and float height.
This may be normal fuel consumption I'm just basing it off other forum posts and my brothers bike.

Thanks in advance

 

[webmaster]

Hi guys, I have just purchased a 2008 Ec250 with a fmf gnarly pipe it's a great bike a lot better than my old Yamaha ttr250.

Anyway I cleaned the carb when I brought it and it's running good apart from the fact it uses almost the whole 9.5 litre tank in about 40km or 3 hours of about half fire roads and half woods. Bearing in mind I'm not flogging it the whole way.
I only found this strange as my brothers kdx 200 only uses about 4.5 litres on the same ride.

The main jet is 175 and a 35 pilot not sure about the needle and float height.
This may be normal fuel consumption I'm just basing it off other forum posts and my brothers bike.

Thanks in advance

First off - our jetting expert, and moderator here, is user "Jakobi". Suggest you send him private message and he can share settings with you.

The oem jetting is cursed with a horrid needle - the 35 pilot indicates you are using this N1EF needle. It will push you into a situation where you are "pulling over". Typically, the idle adjustment is all the way in to the point of being coil bound. The air/fuel in this situation for low speed operation is being primarily supplied by the needle/slide versus the pilot jet/air screw setting. Therefore, you will also find your air screw has little effect, the bike won't idle well, etc.

Get it straightened out by :

1. Install new needle (copy ktm/yamaha or suzuki settings - talk to Jakobi)
2. Turn down idle and reset it with new jetting - otherwise you will still be "pulling over". e.g. some make mistake of leaving in leaner 35 pilot and then crank in idle screw for more fuel/air - and you are back to where you started and "dorked".
3. Use richer pilot jet to complement new needle. Typically 42-45, but will vary depending on riding style, altitude, temps & specific gravity of your local fuel.
4. In this carb - you can go out on air screw and turn down the idle a bit to get slide down further - this gives you more sensitivity on pilot circuit in carb. So don't think you are too rich on pilot if you are 2 to 2 1/4 "out" on air screw. It will be quite happy and have smooth transition into mid...

Jetting is first step. Having head machined to dial in squish band is second step on improving efficiency and have cleaner running...

Jeff

 

[swazi_matt]

should be getting between 60 to 110km on a tank depending on the riding.

very common problem is the float not being set correctly or not closing and you are loosing fuel through the overflow. a quick test is to tape a small container to the fuel overflow and see if it fills over a small bumpy ride.
40km of super rich jetting i suspect would be noticeable because it would have been split with plug changes lol

 

[webmaster]

+1 on checking float height as well.

e.g. my old '01 was dribbling on every uphill and downhill until I set it a little lower...

jeff

 

[(F5)]

I'd just go ahead and replace the float needle valve. Did this for a mates bike that was trucking through gas and fixed it. Any keihin jet for a PWK 34mm or bigger will fit. CR, KX etc.

80km should be easy.

 

[Louis069]

Thanks for the help guys.
I think I'll check if I'm losing fuel through the carb overflow, if i am I'll adjust the float height correctly. If this doesn't make a big enough improvement I'll ask jakobi about swapping out the needle and pilot jet to get it to run cleaner like Jeff suggested. I am away at the moment so I'll let you know how I get on when I get back

 

[Jakobi]

My 2010 chewed a tank in 60kms stock..

80-100kms should be easily achieved. Like others said, set float, take note of what your current jetting is, and roll from there.

Crude check of float is simply lean the bike over. If you get overflow out the carb before around 45 degrees the fuel level is too high.